1. Field of the Invention
In one of its aspects, the present invention relates to a sensor element, particularly for use of vehicular occupant detection system. In another of its aspects, the invention relates to a vehicular occupant detection system.
2. Description of the Prior Art
In recent years, the use of supplementary restraint systems (SRS) such as airbags has become widespread in the automotive industry.
Thus, it is now conventional (and in some jurisdictions mandated) to utilize an airbag-based SRS. Indeed, such systems now utilize airbags which may be deployed from one or more of the dashboard, the A-pillar, the headliner and the like.
While the advent of SRS has, to some degree, revolutionized the automotive industry, there is still room for improvement.
Specifically, as has been widely reported, there can be situations where it is not appropriate for the airbag to fully deploy or deploy at all. Thus, if the occupant in the vehicle seat is a small child, a pregnant woman or a “regular” occupant who is leaning forward, full deployment of the airbag can sometimes lead to unintended (and potential fatal) consequences.
Thus, in recent years, much work has centered on the development on so-called vehicle occupant detection systems which operate generally by providing more information about the occupant in the vehicle seat (e.g., occupant weight, occupant position and the like) and utilize this information to control deployment of the airbag and, in some cases, to disengage deployment of the airbag entirely.
One body of this work relates to the use of strain gauges and the like incorporated in the frame and/or seat pan of the vehicle seat to measure a change in weight when an occupant is seated. While determining the weight of the occupant is useful information, this measurement alone, in most cases, does not provide sufficient information for optimal control of the airbag deployment system.
A second body of work relates to the use of capacitance sensors to map position of the occupant. In some cases, the capacitance sensors can be combined with weight sensors such that the weight and the position of the occupant can be determined. While the use of capacitance sensors in the vehicle occupant detection system is an advance in the art, the long term effects of such a system are unknown. Specifically, it is known that, in order for a capacitance sensor to operate properly, the sensor emit a frequency field which, when interrupted by an occupant, can be detected by the sensor. In other words, whenever the occupant is seated in the vehicle under operation, that occupant will be subjected to the frequency field. Unfortunately, the long term health effects on the occupant of residing in such a field while seated in the vehicle are currently unknown and, at the very least, raises uncertainty as to the overall usefulness of such systems.
Thus, despite advances made in the art, it would be desirable to have a vehicle occupant detection system which provides the advantages of capacitance sensing system (i.e., the ability to map the position of the occupant) while avoiding the requirement for using a frequency field and any long-term health effects on a vehicle occupant residing in that field for an extend period of time.